Catalyst for synthetic-methanol production



Patented Apr. 26, 1927.

UNITED STATES A 1,625,929 PATENT OFFICE,

JOHN C. WOODRUFF AND GROVER'IBLOOMFIELD, F TERRE HAUTE, INDIANA, AS-

SIGNOBS TO COMMERCIAL SOLVENTS CORPORATION, OF TERRE HAU'IE, INDIANA,

A CORPORATION OF MARYLAND.

(iATALYST FOR SYNTHETIC-METHANOL PRODUCTION,

No Drawing. Original application filed May 26,1926, serial No. 111, 84. Dlvided and this application filed October 25, 1926. Serial No. 144,166.

oxides of carbon with hydrogen the pres-.

ence of a suitable catalyst at elevated tem- 1o 'perature and pressure. Carbon monoxide, carbon dioxide, and mixtures of the two oxides may be employed, these substances reacting with hydrogen according to the fol lowing reactions Carbon monoxide-00 2H; CH OH Carbon dioxide-CO 3H CH OH H O It is observed that when carbon dioxide is the oxide employed, one molecule of water is formed for each molecule of methanol produced. On the other hand when pure carbon monoxide is used, theoretically there is nothing produced by the reaction but methanol. Actually in practice pure carbon monoxide and pure carbon dioxide are both dlflicult to obtain economically, so that the methanol synthesis is carried out by reacting a mixture of carbon monoxide and carbon dioxide with hydrogen.

In addition to the reactions producing methanol there are, in the methanol synthesis, undesirable side-reactions which cut down the yield of the desired product. The principal side-reaction which may occur is the formation of methane, which is illustrated below:

In addition to the methane side-reaction there are other side-reactions which sometimes occur in which there are produced esters, aldehydes, organic acids, ketones, and hydrocarbons other. than methane, these reactions occurring as the result of the poly what is equivalent, mixtures of easily reducible metal oxides;

2. Mixtures of oxides of metalsnon-reducible, or difliculty reducible under the-conditions of the methanol synthesis.

In the past, also, one class of easily reducible metal oxides, that is the oxides of iron, nickel, and cobalt have been described as absolutely worthless for the production of methanol catalysts since these metals under normal conditions prevent the formation of methanol, the reactions producing only methane.

lVe have discovered a new type of catalyst which produces a higher yield of methanol than those formerly employed in the art, and at the same time produces a very pure methanol, uncontaminated by byproducts.- An additional advantage accruing from the use of our catalyst is that the formation of methane in the process-with the consequent destruction of valuable hydrogen-is practically eliminated.

We have now discovered a new type of valuable methanol catalyst which comprises three main elements1. e. f

(1) One or more diflicultly reducible metal oxides such as zinc, magnesium, cadmium,

chromium, vanadium, tungsten, uranium, zirconium titanium, aluminium, manganese, molybdenum, thorium, cerium, etc.

(2) One or more easily reducible metal oxides such as copper, silver, iron, nickel, cobalt, etc. 7

(3) A metallic halide.

It-will be observed that in our improved catalyst we ma employ substances normally deleteriousto the methanol reaction-namely the methanating metals-iron, nickel, or

cobalt. In our improved compositions these normall deleterious substances serve advantageous y, apparentl exerting only a normal hydrogenating cata ytic action productive of methanol. Or we may employ easily reducible oxides such as those of copper or silver which are already known in the art I tivity.

(2) The metallic halide interacts with other metallic oxides present in the catalyst to produce oxychloride compounds which, in

turn, either serve as catalyst promoters,or may so modify the purely physical state of the mass as to produce'a more active catalyst;

(3) The metallic halide may be reduced by the high pressure contact with hydrogen and carbon oxides during the commencement of its use as a catalyst and the resultant finely divided metal may increase the catalytic activity, or. alternatively, the me tallic halide may first react with some other metal producing the halide thereof, which may be reduced in the same manner. However, the precise explanation for the improved result attained by the addition of metallic halides to methanol catalysts is not known and forms no part of our invention.

To produce our improved catalysts it is not necessary that the amount of metallic halide added bear any exact weight relation to the remaining constituents of the catalyst, though the amount of halide added should referably be less thanone chemical equivaent of the amount of principal metallic oxide resent in the catalyst.

As illustrative of our invention we will cite a number of examples which show'the ossible methods of preparing and employmg the catalyst which we have discovered. In order to. indicate the efficiency of our catalyst typical results obtained by its use are given below. In giving these specific examples it is our intention'only to thus displa the catalyst efficacy and by no means to imit the scope of our invention. Modifications of the conditions of the reaction will, of course modify the results.

For example, an increased space velocity produces an increased hourly yield and an increase in operating pressure has the same efiect. A change in the temperature will also efiect the rate of conversion of the gases 160 grams chromium nitrate (Cr(NO on o are dissolved, with heating in 60 c. c. water. After the solution has cooled 10 grams zinc chloride and 96 grams ferric nitrate are added. To the resulting cold solution ,100 grams zinc oxide are then added with constant stirring. The resulting wet mass is heated in a orcelain evaporating dish to dryness and hen placed in a copper crucible in which it is heated over a Fletcher burner to drive off the nitrogen peroxide fumes.

The material thus obtained is crushed suiticiently to pass a mesh screen and to it 8.2 grams zinc chloride dissolved in 60 c. 0. water are added." The product thus obtained hardens spontaneously and is olive green 'in color.

The yields of methanol condensate ob tained with this catalyst when a gas mixture comprising 16-17% carbon monoxide and 84-83% hydrogen is passed thru 1 liter of catalyst granules at a space velocity of 20,00075,000, at ,a pressure of 2000 pounds per square inch and 'at a temperature of 400-420" C. will be about 400-950 0. c. of condensate per hour, which analyses 87.6-

v 95.4% by volume of methanol.

Example [1.

7.2 kilograms chromium nitrate Cr (N0 .QH O

and 4.3 kilograms ferric nitrate are dissolved in 5 liters of water by heating in a large porcelain evaporating dish on a steam bath. 450 ams zinc chloride (which may contain 0.0002% arsenic) are then dissolved in this solution.

Separately thereis made up a suspension of 4.5 kilograms zinc oxide (which may contain traces'of chlorides and heavy metals slightly in excess of U.-

P. limit) in 11 liters ofwater. By stirring this suspension well and breaking up by hand any lumps that form, a practically complete suspension is obtained. To this suspension there is slowly added with vigorous stirring the above solution of salts. A thick pasty mass is formed which is spread out in a tlnn layer to dry and harden. To accelerate this process, a current of air from an electric fan may be allowed to play on the surface of the mass. On the following day, the hardened mass is broken upand placed in a furnace contains the catalyst and thru which a cur- 4300 grams ferric nitrate and 450-820 rams rent of gas composed of -25%. carbon monoxide and 8575%'hydrogen is passed.

The mass is heated until the temperature registered by a pyrometer placed in the center of the copper vessel reaches approxi mately 350 C. and the heating continued at this temperature until nitrogen peroxide q 25.6-26.1% ferric nitrate, and 4.8'.2.7% zinc fumes are no longer given off When a gasmixture comprlsing 1060% carbon monoxide and 9040%-hydrogen is passed over this catalyst at a temperature of 400-420C. at a space velocity of 20,00O-40,-

' composed to the oxide by sim le heating at-a temperature-of 385-400 000, and at a pressure of 3200-3500'pounds per square inch, from 1.5 to 2.5 liters of condensate per hour per liter of contact mass,

analyzing 93.097.2% by volume of methanol, are obtained.

Eacmple Ill.-

' 7 When ag'as mixture comprising 25% by volume carbon dioxide and 75% by volume hydrogen is passed over the catalytic mass prepared as described in Examgle II above, at aspace velocity of 20,00040,000, and at ap'ressure of 3500 pounds per square inch, a yield of 2.0-4.0 liters of condensate per hour er liter of catal st, analyzing 65% by vo ume of methano is obtained. i

It will be noted that in both of the. herein described specific examples, the catalyst mass, as finally prepared for use, comprises zinc oxide. chromium oxide, lIOIl oxide, and I of hydrogen a temperature of pp fi mately 350 C until nitrogen peroxide fumes.

zinc chloride. In the case'of Exainple -I the nitrates of chromium and iron were dethe dry mass. In, the/ ease 0 Example II, this reduction was accomplished by means of a mixture of carbon monoxide andhydrogen.- The effect on the composition is the same in both treatments. 1 Y

Broad claims relating to the use of mix tures of diflicultly reducible oxides with 0x idesof iron group metals and metallichalides as methanol catalysts -have been resented in our Serial Application 111,884 ed May 26, 1926, hence on yspecific claimsarc presented herein, P

Now having described our invention we claim the iollowing'as new and novel I 1. A methanol catalyst-initially comprising' zinc oxide, chromium oxide, ironoxide an zinc chloride. I

2. A methanol catalyst prepared by com- A chromium nitrate r man-mic).

ared by comchloride inaqueous mixture, and converting the nitrates to oxides.

4. A rocess for the preparation of a 'methano catalyst which comprises adding an aqueous solution consisting of chromium nitrate v u ie).- 9H.0 ."1

process for the preparation of a a ferric nitrate and zinc chloride to an aqueous an aqueous solution'consisting of 42.9-43.970

chromium nitrate 256-2617;; ferric nitrate and 48-27% zinc no longer given off; Y I

\ A processfcr the production of synthetic methanol which comprises passing a mixture" of hydrogen and oxides of carbon at a pressure in excess of 2000 pounds per @uare inch and at a tem erature-above 250 over a catalyst mitia y com rismg zmc ox de, chromium oxide, iron 0x1 e, and-z1nc chloride, cooling the reacted gases, and recovering the resultant methanol.

7. Af rocess for the production ofsyntheticvmethanol which comprises passing. a

, mixture of hydrogen and oxides of carbonat pounds per apressu're m;excess of 2000 square inch a'nd'at a tem era ture to 385-420 C. over -a-catalyst initia y com rising zinc oxide, chromium oxide, iron 0x1 e; andfzmc chloride, cooling the reacted gases, and rebining 4500 grams zinc oxide, 7200grams covering the resultant methanol. }'In testimony whereof we'aflix our; signa- JOHN c. .WOODRUFR' GBOVER BLOOMFIELD. 

